JPS5970579A - Driving method of ink jet head - Google Patents

Abstract

PURPOSE:To uniformize flying velocity of ink droplets and prevent the generation of satellites to contrive to enhance printing quality, by impressing an appropriate driving voltage on a head in accordance with preceding and subsequent printing informations. CONSTITUTION:A series 8 of pulse signals are sequentially inputted into a shift register 9 provided as a series-parallel converting means, a predetermined number of bits at a time. A pulse signal 10 at a predetermined position is inputted into a counter 11 as a clearing pulse, and a series M of pulse signals inputted precedently to the pulse signals 10 and a series N of pulse signals inputted subsequently are inputted into an ROM12 as parallel signals. Various kinds of voltage wave forms are previously stored in a memory device 12, and one of the voltage wave forms 13 is selected in accordance with a combined pattern of the series M, N of pulse signals, and a voltage to be impressed for driving a piezoelectric element 6 is fed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of driving a so-called on-demand type inkjet head, in which ink droplets are ejected from the Infusiera 1 head only when necessary.
In particular, the present invention relates to a method of driving an inkjet head that aims to improve printing quality when the repetition frequency of ink droplet ejection is reduced.

An inkjet printer is known in which ink droplets are ejected from the nozzle portion of an Infusiera 1-\RAD, and the ink droplets fly toward a recording medium and are recorded as dots on the recording medium.

Ink Jets] In a complete printer, when the repetition frequency of ink droplet ejection is increased for high-speed printing, the ink movement in the head and nozzles cannot follow, and the ink response is delayed.In such a high frequency range, , the flying speed of the ejected ink droplets changes due to the influence of past ejections.When the flying speed of the ink droplets changes,
Dots recorded on a moving recording medium are deviated from their intended recording positions, resulting in poor print quality. Furthermore, in the high frequency range, the ink in the head and nozzles also fluctuates greatly, making it easier for air to be sucked in from the nozzles, and when air is sucked in, there is a problem that ejection becomes impossible. moreover,
In the high frequency range, the ink droplets are ejected from an unstable state, so the problem is that it is easy to generate undesirable minute ink droplets that occur around the main particles of the ejected ink droplets. There is also.

Stabilization of ink droplet ejection in high frequency range -2534
In Publication No. 0, the difference between the continuous printing part and the intermittent printing part is ', *
<``J' J, uni, a method has been proposed to determine the drive voltage of the head by reading the past average history (manpower density). The state of the ink before ejection is not just the input density of the past print signal, but also the pattern of the print. For example, it has become necessary to have finer control over the printing pattern, since it is largely dependent on the order in which the ink droplets are ejected at J or U spacing.

J, Depending on the printing pattern, resolite may be generated, and if it occurs in the printing pattern, the printing will be disturbed, so it is necessary to have an inkjet head driving method that does not generate resolite depending on the printing pattern. It has become.

The purpose of the present invention is to improve printing quality by equalizing the flying speed of ink droplets and preventing the occurrence of υ tail 1~ in a high-speed printing area where the frequency of ink droplet ejection is high. The purpose is to prevent air from being sucked in and improve the reliability of the device.

The inkjet head driving method of the present invention that meets this objective converts a sent pulse signal into a drive voltage signal, drives the inkjet head in accordance with the drive voltage signal, and drives the inkjet head to form ink droplets. J3 is a method for driving an inkjet head that ejects inkjet head, and converts the pulse signal into a drive voltage signal by (a) inputting a series of pulse signals sent in series sequentially by a constant number of bits into a serial-to-parallel conversion means; (1) On the back of the pulse signal series manually input to the serial-parallel conversion means, a pulse signal at a predetermined position is used as a drive-on A-no-shintan to eject ink droplets from the inkjet head, and C is not taken out. , a pulse signal sequence inputted before the signal and inputted after the signal 4
1. Extract the pulse signal series etc. as parallel signals, and (
C) Various 7h pressure waveforms are stored in advance in C1 according to the combination μ of the previous fj and subsequent pulse signal series patterns ts
The present invention is comprised of the following method: (d) selecting a negative voltage waveform from the storage device; and (d) determining a driving voltage signal for the Infusiera 1 to head based on the selected voltage waveform.

The drive voltage of the ink jet head that ejects ink droplets by this method is determined by the preceding pulse signal series (previous print information), the subsequent pulse signal series (subsequent print information), and J That is, the ejection pattern of the 729 ink droplets ejected earlier and the ejection pattern of the ink droplets ejected later are corrected to the optimal applied voltage determined in advance by J.

With this correction, the ink droplets are ejected with a driving force according to the state of the ink before ejection, and the speed of the ink droplets flying toward the recording medium is made uniform. Also, since it is also controlled by the subsequent printed information,
properly protected.

By making the flying speed of ink droplets uniform and preventing satellite light <1-1-1-1, good printing quality can be obtained even at speeds. In addition, the optimal voltage and voltage waveform are applied according to the ink condition in the nozzle and head before ejection. The build-up is prevented and the reliability of the device is improved by preventing air intake from the nozzle.

Preferred embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an apparatus and its operation for carrying out a method for driving an ink cartridge 1-head according to an embodiment of the present invention.

FIG. 1 shows the enclosure configuration of the Infusiera 1 complete printer. In the figure, numeral 1 is a cylindrical ink jet head, the inside of which is filled with ink. White ginseng 1 is ejected at the tip of the inkjet head 1 (31 nozzles 2 are provided, and the ink particles 3 are ejected from the nozzles 2 onto the recording medium L' attached to the surface of the drum 4 which is rotationally driven). It has become so. A piezo element 6 is attached to the outer periphery of the inkjet head 1, and the volume of the cylindrical head 1 is expanded by the piezo electrostrictive force of the piezo element 6.
The ink droplet 3 is ejected from the nozzle 2. The drive voltage applied to the bi-zo element 6 is sent from the control device 7, A signal for ejecting the ink droplets 3 is sent as a pulse signal from a memory or the like.

The pulse signals sent to the control device 7 are 1J and 111 pulses as shown in FIG.
．． 1.1.0.1" is manually input, the control device responds to the signal 11-1 with - 6, and no drive voltage is generated for signal 10''.

Fig. 2 is a block diagram of the control device 7, and Fig. 3 is a block diagram of the control device 7.
Accept the processing status. The pulse signal series 8 sent in series to the control device 7 is input to the register 9 to shift 1 as a serial-to-parallel conversion means, where K>Q, and the pulse signal series 8 is input to shift 1 to register 9. Fixed bin 1 to feed
A few people are horned. In this embodiment, as shown in FIG. 3(A), 6 bits are manually input one by one. The shift register 9 inputs the pulse signal 10 at a predetermined position in the pulse signal sequence 8 to the /j6 bit 1, and in this embodiment, the pulse signal 10 in FIG. 3 (Ll
) The fourth input pulse signal as shown in J is input to the counter 1-1 as a clear signal. Pulse signal 10J at a predetermined position of pulse signal sequence 8 to 6 bits 1:
The pulse signal sequence M that was input earlier and the pulse signal sequence N that was input subsequently (Figure 3 (b)) are taken out as parallel signals and stored as a 110M memory device (read-on-me-seven). 12 is input. Record 11'! Device 1
2 (This means that the waveforms of various types of electricity are stored in advance.
Among these, the combination of the pulse signal series MSN with the negative voltage waveform is selected according to the pattern. The pre-stored voltage waveform 13 is stored as, for example, a 100-pulse cycle signal train, and is shown in FIG. 33(C).
Various waveforms A3J such as lean-in curves and various scale amplitudes are stored.

The actual generation of the selected voltage waveform 13 is performed by incrementing the output of the counter 11, which is stored in the memory 12. The counter 11 is cleared by the signal 1-1j of the pulse signal 10 at a predetermined position of the jitter register 9, and its output is advanced. The output of the counter 11 is advanced in accordance with the signal of the reference clock 14 connected to the counter 11, so that the output of the counter 11 becomes the number necessary to generate the voltage waveform 13 stored in the storage device 12. The clear gate 15 is closed and stopped 1 to prepare for the next clear signal. Therefore, the storage device 12 stores "
Only in this case, when 11 pulse signals are input, the 1F waveform 13 selected by the combination of pulse signal sequences M and N is generated.
actually occurs.

The voltage waveform 13 selected in the storage device 12 is input to the head amplifier 17 after being converted into an analog signal (FIG. 3(d)) by a D-Δ converter 16 (digital-to-analog converter). The applied voltage is suitably amplified by the head amplifier 17 and sent to the piezo element 6 of the inkjet head 1 for driving.

In the method of driving the head to the infusier 1 of the present invention operated in this manner, the waveform of the driving voltage of the inkjet head 1 for ejecting the ink droplets 3 is based on the preceding print information M and the subsequent print information N. Determined by a combination of patterns. That is, while considering the ejection interval of the ink droplets ejected earlier, the strength of the driving force for ejection, and the ejection interval of the ink droplets 3 ejected later, and the strength of the driving force for ejection, The driving voltage and its waveform for ejecting the ink droplets 3 are determined.

The relationship between the print information M, N and the voltage waveform to be selected can be determined in advance through a test. That is, through the test, the relationship between various combinations of the preceding and succeeding print information M and N and the flying speed of the drive type for ejecting the ink droplets 3 is confirmed in advance. Based on this relationship, σ, preceding and subsequent printing information M
, H, the optimum driving voltage waveform is selected to make the flying speed of the actually ejected ink droplets 3 uniform f8 degrees. By applying the optimal driving voltage selected in this way to the head 1, even when the state of the ink in the nozzle 2 and the head 1 in the high frequency region is unstable,
The driving force for ejecting the ink droplets 3 according to the state is given,
The ejected ink droplets 3 fly at a uniform speed. By making the flying speed of the ink droplets 3 uniform, even if there is a relative movement between the nozzle 2 and the recording medium 5,
The ink droplets 3 reach a predetermined position on the recording medium 5 with high accuracy, and good print quality can be obtained. In addition, when selecting the drive voltage waveform, the printed connection information N is also taken into consideration.C1
The occurrence of rear light when the ink droplets 3 develop as flying particles can be prevented. The print quality is further improved by preventing the occurrence of satellites.

In addition, by selecting the driving voltage waveform according to the state of the ink in the nozzle 2 or the head 1, generation of a driving force that increases ink fluctuations such as resonance with ink fluctuations, for example, is prevented, and the voltage waveform Depending on the situation, it is also possible to apply a driving force in a direction that suppresses excessive fluctuations in ink. By suppressing large fluctuations in the ink in the nozzles 2 and the head 1, suction of air from the nozzles 2 is prevented, and good operation of the apparatus is maintained stably.

In this example device, a cylindrical pressure pulse head with a nozzle diameter of 40 μm and an outer diameter of 5 mm, and an applied voltage of 90 V P -P
, pulse width 67 μsec, ff1I waveform sine curve, shift register manual bit number 6 bits, preceding print information 3 bits, subsequent print information 2 bits, shift register input pulse signal sequence [1, 1, 1, 1, 0, FIG. 4 shows the results of measuring the flying speed of the ink droplets 3 under the conditions of 1. In the case where the driving voltage was corrected according to the present invention, the particle velocity was much more uniform than in the case B when the driving voltage was not adjusted, and the printing quality was greatly improved. Further, FIG. 5 shows the printing results when the preceding printing information is set to t) bits and the subsequent printing information is set to 2 bits (1 to 1). When the drive ffi J:E was not corrected, printing disturbances and the occurrence of reply l-G were observed, but as a result of adopting the method according to the present invention, good printing quality was obtained and the occurrence of sub-light was observed. It is also prevented.

In addition, in the above embodiment, the number of preceding and subsequent printed information M −
Let us explain the case where i-N is several pips 1-.
, N is as good as people! ! IJ voltage correction becomes more precise. A sufficiently practical printing quality improvement effect was obtained at M2S and N≧2.

When setting the preceding printing information M to a large value, it is thought that the effect on the current ejection of ink droplets is smaller as the preceding printing information M
Divide into I'-L M z, coarser for the more preceding M+ bits, and M? which is closer and has more influence. It is also possible to precisely correct the pitch 1. In this way, when there are many combinations such as J and M≧10, it is effective to reduce the number of combinations.

Subsequent N-pi! Regarding ~ (also, by the same means, with a smaller number of unions U, the same effect as the supplementary IT of
! When using the inkjet head drive method of the present invention as explained above, the ink droplet ejection is controlled by print information before and after the ink droplet ejection. J to decide the drive type n2 signal, sea urchin! [C] Even in the area where the repetition frequency of ink droplets is high, it is possible to obtain good printing quality without printing disturbances or occurrence of reply 1, and high-speed printing is possible.
Ru. The result is an on-demand inkjet! For J3 in ζ, the conventional limit frequency is 3Kt-1
I've had z# times, but the frequency of 10 Kl-1z"- is ITJ (ll: What...)l.

In addition, since the driving voltage is determined according to the state of the ink in the head and nozzles, large fluctuations in ink can be suppressed, air can be prevented from being sucked in from the nozzles, and the efficiency of the device can be reduced by 1q. .

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an inkjet 1-71~ type printer of the present invention, FIG. 2 is a 1179 diagram of the control device m of the device in FIG. Figure 1 is a diagram showing the relationship between ink particle velocity and particle number. Figure J is a printed map from the I-Sung Dynasty. 1......, Inkji Dot Head 2...
...Nozzle 3... Ink droplet 5 ... Recording medium 6 ... Pi1zo element 7 ... ...Control equipment 8...Pulse signal sequence 9...Serial-to-parallel conversion means and shift register 10 ()... ...Pulse signal 11 at a predetermined position...
......Counter 12...Memory 8A position 13...Pre-stored voltage waveform 1
4・・・・・・・・・Standard [1 Tsuk 15・・・・・・
...Gate 16...D-△ converter 17...Amplifier M...Previous pulse signal sequence N...
...Subsequent pulse signal sequence 42

Claims (1)

[Claims] (1) In an ink jet head driving method, the inkjet head is driven to eject ink droplets by converting a sent pulse signal into a driving voltage signal and driving an inkjet head according to the driving voltage signal, The conversion from the pulse signal to the driving voltage signal is performed by (, C
) The pulse signal series sent in series is input to the serial-to-parallel converting means one to a certain number of bits at a time, The pulse signal of the position is extracted as a driving signal for ejecting ink droplets from the inkjet head, and the pulse signal series inputted before the signal and the pulse signal inputted after the signal are extracted. Extract the series as parallel signals, (c)
Selecting a negative voltage waveform from the above device in which various voltage waveforms are stored in advance according to the combination of patterns of the preceding and succeeding pulse signal series, (d) Based on the selected voltage waveform, performing the above-mentioned 1. A method for driving an inkjet head, comprising: determining a drive voltage signal for the inkjet head.